Although hypertensive crisis, status epilepticus, and accidental deaths (e.g., drowning) have been implicated, respiratory arrest is probably the most frequent cause of deaths that have accompanied the increased abuse of phencyclidine (PCP). Antidotes are available to help manage the hypertensive, convulsive and pyschotic reactions seen in PCP overdosage, but none has been found for the respiratory depression. This project is aimed at assessing the effectiveness of atropine, naloxone, and classical analeptics (e.g. doxapram) in reversing the hypertension, apneusis, respiratory depression and hypotension induced by acute iv PCP infusion. The ultimate aim of these animal studies is to provide the basis for the most effective clinical management of this important and sometimes lethal respiratory manifestation of overdosage with PCP-type drugs of abuse in man.